1. Field of the Invention
The present invention relates to a package for an optical semiconductor in which a light-emitting device and a light-receiving device are placed within a single package.
2. Related Background Art
FIG. 14 shows a conventional light-emitting/receiving device. In this drawing, reference numeral 100 denotes a bottomed device case whose inside is divided into two inside portions by a partition board 102.
Reference numerals 103 and 104 denote lead frames that respectively have supporting portions 103a and 104a at their tips. These lead frames are allowed to pass through a side portion of the device case 100 and are fixed to the device case 100. In more detail, the tip of the lead frame 103 is allowed to enter into one of the two inside portions of the device case 100, while the tip of the lead frame 104 is allowed to enter into the other of the two inside portions of the device case 1. Reference numerals 105 and 106 represent lead frames for connection and these lead frames 105 and 106 are allowed to pass through an opposite side portion of the device case 100. Each tip of these lead frames is allowed to enter into the device case 100 and is fixed to the device case 100 so as to oppose one of the tips of the lead frames 103 and 104. Also, a light-receiving device 107 is mounted on the supporting portion 103a of the lead frame 103 and a light-emitting device 108 is mounted on the supporting portion 104a of the lead frame 104. The light-receiving device 107 is connected to the lead frame 105 through a metallic wire 109 and the light-emitting device 108 is connected to the lead frame 106 through a metallic wire 100.
In the device case 100 described above, a transparent resin material in a liquid state is filled into each of the two inside portions and is hardened. This transparent resin material is filled so that its volume becomes smaller than the volume within the device case 100, thereby avoiding its overflow from the device case 100. Then, the transparent resin material is hardened, thereby protecting the light-receiving device 107, the light-emitting device 108, and the metallic wires 109 and 100 within the device case 100.
The optical semiconductor package described above is produced in a manner such that the rear end side of each of the lead frames 103, 104, 105, and 106 protruding to the outside of the device case 100 is fixed to tie bars 111 and 112 so that a plurality of optical semiconductor packages are produced so as to be connected with each other. Then, the tie bars 111 and 112 are cut and respective optical semiconductor packages are finally obtained, as shown in the drawing.
The optical semiconductor package described above has the following problems. First, the lead frames 103, 104, 105, and 106 provided for the optical semiconductor package are produced using a method such as etching, so that the price of the optical semiconductor package rises and it is difficult to bring down the price. Also, the frames 103, 104, 105, and 106 are delicate, so that it is required to pay close attention to handling of these frames during production work and therefore work efficiency is impaired.
Also, the mounting of the light-emitting device 108 and the light-receiving device 107 and the connecting of the metallic wires 109 and 110 are machine work but the opening portion of the device case 100 is extremely narrow (around 1.5 mm×2 mm, for instance), so that the work range of the machine is limited and therefore the machine work is slowed.
The liquid resin material having a light transmission property is filled in the device case 100 and is hardened. When doing so, the resin material is filled so that its volume becomes smaller than the volume within the device case 100, thereby avoiding overflow of the resin material from the device case 100 at the time of filling of the resin material. In this case, however, the surface shape of each of a light emitting portion and a light incident portion becomes like a concave lens, so that there occurs a problem that the enhancement of device accuracy is hindered by diffusion of light.
Further, positions of the protrusions of the lead frames 103, 104, 105, and 106 are elevated from the undersurface of the device case 100. Therefore, it is required to form the lead frames 103, 104, 105, and 106 so that these lead frames contact a mounting substrate when the optical semiconductor package is mounted on the mounting substrate. As a result, it is required to spend time and effort. In addition, the optical semiconductor package uses the device case 100, so that it is difficult to miniaturize the optical semiconductor package.